/* ***************************************************************************
 *
 * ftgasp.h
 *
 * Access of TrueType's 'gasp' table (specification).
 *
 * Copyright (C) 2007-2021 by
 * David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 * This file is part of the FreeType project, and may only be used,
 * modified, and distributed under the terms of the FreeType project
 * license, LICENSE.TXT.  By continuing to use, modify, or distribute
 * this file you indicate that you have read the license and
 * understand and accept it fully.
 *
 */


#ifndef FTGASP_H_
#define FTGASP_H_

#include <freetype/freetype.h>

#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif


FT_BEGIN_HEADER


/* *************************************************************************
 *
 * @section:
 * gasp_table
 *
 * @title:
 * Gasp Table
 *
 * @abstract:
 * Retrieving TrueType 'gasp' table entries.
 *
 * @description:
 * The function @FT_Get_Gasp can be used to query a TrueType or OpenType
 * font for specific entries in its 'gasp' table, if any.  This is mainly
 * useful when implementing native TrueType hinting with the bytecode
 * interpreter to duplicate the Windows text rendering results.
 */

/* *************************************************************************
 *
 * @enum:
 * FT_GASP_XXX
 *
 * @description:
 * A list of values and/or bit-flags returned by the @FT_Get_Gasp
 * function.
 *
 * @values:
 * FT_GASP_NO_TABLE ::
 * This special value means that there is no GASP table in this face.
 * It is up to the client to decide what to do.
 *
 * FT_GASP_DO_GRIDFIT ::
 * Grid-fitting and hinting should be performed at the specified ppem.
 * This **really** means TrueType bytecode interpretation.  If this bit
 * is not set, no hinting gets applied.
 *
 * FT_GASP_DO_GRAY ::
 * Anti-aliased rendering should be performed at the specified ppem.
 * If not set, do monochrome rendering.
 *
 * FT_GASP_SYMMETRIC_SMOOTHING ::
 * If set, smoothing along multiple axes must be used with ClearType.
 *
 * FT_GASP_SYMMETRIC_GRIDFIT ::
 * Grid-fitting must be used with ClearType's symmetric smoothing.
 *
 * @note:
 * The bit-flags `FT_GASP_DO_GRIDFIT` and `FT_GASP_DO_GRAY` are to be
 * used for standard font rasterization only.  Independently of that,
 * `FT_GASP_SYMMETRIC_SMOOTHING` and `FT_GASP_SYMMETRIC_GRIDFIT` are to
 * be used if ClearType is enabled (and `FT_GASP_DO_GRIDFIT` and
 * `FT_GASP_DO_GRAY` are consequently ignored).
 *
 * 'ClearType' is Microsoft's implementation of LCD rendering, partly
 * protected by patents.
 *
 * @since:
 * 2.3.0
 */
#define FT_GASP_NO_TABLE -1
#define FT_GASP_DO_GRIDFIT 0x01
#define FT_GASP_DO_GRAY 0x02
#define FT_GASP_SYMMETRIC_GRIDFIT 0x04
#define FT_GASP_SYMMETRIC_SMOOTHING 0x08


/* *************************************************************************
 *
 * @function:
 * FT_Get_Gasp
 *
 * @description:
 * For a TrueType or OpenType font file, return the rasterizer behaviour
 * flags from the font's 'gasp' table corresponding to a given character
 * pixel size.
 *
 * @input:
 * face ::
 * The source face handle.
 *
 * ppem ::
 * The vertical character pixel size.
 *
 * @return:
 * Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no
 * 'gasp' table in the face.
 *
 * @note:
 * If you want to use the MM functionality of OpenType variation fonts
 * (i.e., using @FT_Set_Var_Design_Coordinates and friends), call this
 * function **after** setting an instance since the return values can
 * change.
 *
 * @since:
 * 2.3.0
 */
FT_EXPORT(FT_Int)
FT_Get_Gasp(FT_Face face, FT_UInt ppem);

/* */


FT_END_HEADER

#endif /* FTGASP_H_ */


/* END */
